1. Field of the Invention
The present invention relates to filter processing technology for images.
2. Description of the Related Art
In recent years, there has been an increase in the screen size of a display and the resolution thereof (4K2K, 8K4K). Along with this, there is a demand for generating images with high quality in image processing such as resolution conversion. Filter processing using a two-dimensional filter is one of such image processing methods. A method of increasing the number of filter taps is one method for improving quality of images obtained by performing filter processing. However, in order to increase the number of taps, it is necessary to expand a calculation circuit, a line memory, and the like.
Japanese Patent Laid-Open No. 9-214864 discloses a method for enlarging image data while preventing such expansion of a calculation circuit, a line memory, and the like. In the method described in Japanese Patent Laid-Open No. 9-214864, a plurality of sub-frame images are generated by performing interpolation so as to repeat a pixel value of an adjacent pixel when performing enlargement processing. At this time, it is possible to cause pixels at the same position in different sub-frame images to have different pixel values. The average of the pixel values in the frame images will serve as an apparent pixel value by successively displaying such a plurality of frame images.
However, in the method disclosed in Japanese Patent Laid-Open No. 9-214864, a pixel value generated by interpolation is a repetition of another pixel value. It is desirable to perform image processing with higher precision in the present situation in which there is a demand for higher image quality.